Internal-combustion engine.



. UNITED STATES PATENT OFFICE.

CHARLES DAVID MCCLINTOCK, OF- OAKLAND, CALIFORNIA, ASSIGNOR OF ONE-HALFTO SAMUEL RUSSELL BOGUE, SAN FRANCISCO, CALIFORNIA.

INTERNAL-COMBUSTION ENGINE.

Specification of Letters Patent.

Patented May 25, 1909.

Application filed June 23, 1908. Serial No. 439,957.

ioned wall of the combustion chamber, of-

means for increasing and decreasing theresistance of said Wall andallowing it to move during the compression of the charge.

In practice my invention will be carried out by a construction in whichthe usual rcciprocating piston, here called the working piston, acts inconjunction with another reciproeating piston, here called the airpiston, both pistons being adapted to work in the same cylinder, or inseparate cylindersconnected' to each other by a pass-Way or port, theair iston being adapted to separate the usual c earanee space into twoparts; that part 'between the two pistons being here called thecombustion chamber, and that part between the air iston and the lixedead of the cylinder bemg here called the air chamber.

In connection with the several results of this type of internalcombustion engine, to-

Wit, to thoroughly scavenge or clear the combustion chamber of thenon-combustible or Waste products of each explosion before theintroduction of the fresh charge of explosive mixture for the nextexplosion 3 to provide an air chamber affording an elastic-cushion toreceive the impact or percussion effect of the explosion of the charge(which occurs before the end of the compression stroke of the Workingpiston) and thereby greatly lessen the back pressure 0n the Workingparts of the engine, and at the same time, reduce vibration; and tostore up the energy of the impact or percussion effect of each explosionin this air chamber, in the form of compressed air to be usedimmediately thereafter to perform Work (through the medium of the freemoving air piston and the gases in the combustion chamber) on theworking piston of the engine, the object of my invention is to regulatethe pressure of air in the air chamber by means under-- control of asuitable governor', or by hand, in such a way as to vary the volume ofthe combustion chamber or clearance space, as it is commonly called, ata certain pre-determined ratio to the quantity of explosive mixturetaken into thc cylinder during the suction stroke. of the workingpiston; thus cll'ecting' the ignition of the explosive charge at nearlycrmstant pressure for any quantity of the con'ibustible, Whether fullclmrge or a fraction oll the full charge, and thereby obtaining nearlythe same terminal or maximum pressure, with consequent economy of fuelfor all practical variations, of the quantity ol" the explosive charge.This feature of variableI clearance, asl call it, also makes the enginecontrollable to a degree not possible with cngines burning their chargeof explosive at constant volume and variable pressure in a combustionchamber of {xed volume, it having been found that the combustion ofgases or explosive mixtures ol' air and oil-vapor in closed cylinders isgreatly aided by compression before ignition, and, also, that a higherpressure is obtained by such combustion under pressure. This device aimsto keep the pressure of ignition practically constant for all quantitiesof the explosive charge. The volume of each explosive charge is to bereg'ulated by the usual means of throttling, or by some suitablepositive cut-oil mechanism controllable by the usual governor, or byhand. I attain these results by the mechanism illustrated in theaccompanying drawings, in which Figure 1, is a vertical section of myinternal combustion engine, the pistons beingat the end of theirrespective instrokes, this being their relative position at the instantof coinplete cxpulsion of the burned products of the previous explosion.Fig. 2, is a verticalsectior showing the relative position of thepistons at the instant of the explosion of the charge in the combusthmchamber. Z-.l is a sectional view showing the air piston in a chamberseparate from the engine cylinder,V but communicating therewith.

The main cylinder 1, with its water spaces 2, its inlet valve 3 andinlet opening 4, its exhaust valve 5 and' exhaust opening its workingpiston 7 and co-acting connecting rod 8, and its port 9, are,substantially, the same, in arrangement and operation, as in otheri1iternal-eonibustion engines.

ln Fig.A 2, the line A-B, marks, approximately, the top or outer end ofan ordinary single acting' cylinder as in common use on internalcombustion engines, and the portion of the cylinder shown in this figureabove this line is, in'this form, an vextension of the cylinder Whichprovides forthe air piston v and the air chamberl 11. In adapting myinvention to an ordinary single acting cylinder the com I prefer thisform of extending or lengthening the cylinder, as shown, the piston 10fittingf closely, buttfree to move therein, and being adapted toseparate the air chamber 11, from the combustion chamber 12.

To the air iston 10, and co-acting there- With, is attac ed the guiderod or stem 13, Working in and closely fittin "the opening in thecylinder head 11,6. Attac ed to the'guide rod 13 isthe small/cylinder17, thesame being threaded and screwed on the guide rod 13, and furthersecured by the lock nut 18. The fixed piston or collar 19 on thecylinder head 16 is adapted .to fit closely to the inner Walls ofthesmall cylinder 17, forming the inclosed air s ace 20 which is desi nedto provide an elastic-cushion to check t e instroke of the air iston 10,and revent it from coming in vio ent contact With the Working piston 7.The small opening or port 2,1 connects the adjustable relief valve 22with the air chamber 1 1, and the said relief valve is adapted to openautomatically When the pressure in the air chamber 11 reaches a maximumfor Which the relief valve has previously been set.

The object ofthe adjustment of the maximum pressure in the air chamber11. is apparent by the following LetY it be assumed that the engine isjust started, and the air in the air chamber 11 stands at thetemperature and pressure of the atmosphere. It will be seen that the airin the air chamber 11 Will become heated as the engine warms up afterstarting andthe increase of ressure, due to the lair being confined,Will, y resisting the compression of the charge and reducing the volumeof the clearance space, cause a higher pre-com ression oftheexplosivecharge in liustion chamber 12. Thus, by adjusting the maximum pressurein 'the air chamber 11 by means of the relief valve 22, (whichadjustment Will also fix the minimum pressure) a Wide range ofpre-compression pressures may be had. This feature readily.

adapts the engines to the use lof different fuels, requiring differentdegrees of pre-compression for their proper combustion, and it alsoprovides a means for adjusting the en- .gine to the use of'any one kindof explosive mixture in such a Way as to obtain complete 4 combustionand the maximum amount of for limitin the maximum Work for the fuelconsumed.

' The relief valve 22 only provides a means ressure, as -by loosening te spring by Whic it is adjusted, it will allow some of the air in theair chamber 11` to escape, and thereby reduce' both the maximum andminimum pressure; or by tightening-the s ring, the pressure in the airchamber 11 `Wil rise to the maximum pres# sure for which the reliefvalve 22 is set'before allowing any of the air in the air chamber toescape in the air' reservoirn hereinafter' described, thereby maintainina higher precompression pressure in 4t e combustion chamber 12 byreducing its volume.

The action or operation of an internalcombustion en ine of this type, asfar as described is as fol oWs z-On starting the engine Ilet it beassumed that the'Working piston. 7

immediately after the Working piston 74 starts on its first out-stroke.The opening of this inlet valve 3 admits the charge or explosive mixturewhich flovvs into the combustion chamber 12 as the Workin piston 7recedes. This operation, When a ful charge of the explosive mixture isrequired, continues to the end of the first out-stroke, commonly calledthe suction stroke", at Which-point the inlet valve 3 closes and theWorking iston 7 starts on its first in'stroke, common y called thecompression stroke. It Will be noted that the air piston 10 remainsstationary during this first out-stroke or suction stroke of the Workingpiston 7. NOW, at

the beginning of the first in-stroke or compression stroke gof theWorking iston 7 the valves 5 and 3 b eing closed, the c arge in thecombustion chamber 12 stands at approximately, the pressure of theatmosphere, and

Aas the piston 7 advances, the volume `of this charge is reduced .andits temperature increased, both bytheat-tendant compression, and bycomin in contact With the heated Walls of the4 cyinder 1. and thepistons 7 and `10. These combined conditions cause a to move on itsfirst outestroke, thereby compressing the air in the air chamber 11 andmaintaining a practical balance of pressuresv in the air chamber 11 andthe combustion chamber 12 throughout the compression stroke". Near theend of this compression stroke and When the proper pre-compression ofthe charge has been. attained the Vcharge is ignited, and explodesviolently in the combustion chamber 12, causing an im.- mediate rise ofpressure therein, 'which instantly forces ,the air piston 10 stillfarther f has int'o the air chamber 11 until a practical balance ofpressures has again been reached in the two chambers. Let it be nowassumed that the working piston 7 and the air piston 10 have reached theend of their res ective compression strokes, and that the ighesttemperature of the burning charge and maximum pressure in both thecombustion chamber 12 and the air chamber 11 have been attained. 1tshould be remembered that the ultimate stroke of the air piston 10 isonly about three-tenths of the stroke of the working piston 7 and thatafter the maximum precom ression in the combustion chamber 12 eenreached, the greater part of the stroke of the air iston has been made;therefore, a very smal movement of the air-piston 10 at the time of theexplosion of the charge is sufficient to greatly increase the pressureof the air in the air chamber 11,'and, also, that this slight movementof the air iston, caused by the explosion of the charge, as no materialeffect on the pressure or volume of the burning gases, the combustionchamber 12 now being comparatively large, and the air chamber 11 small.The compression and expansion of the air and the gases forming the exlosive charge, follow very nearly the law, 'lressure times volume equalsa constant. its second out-stroke, commonly called the working stroke orimpulse stroke, and

the pressure of the gases in the combustion.

chamber 12 immediately begins to fall as the f gases expand. At, thesame time the compressed air in the air chamber 11 also begins toexpand, always tending lto keep a ractical balance of pressure in thetwo cham ers, and driving the air piston 10 on its in-stroke. Thisexpansion of gas and air continues throughout the working stroke. A

The air piston 10 may be considered as merely floating between the gasesin the com- -bustion chamber 12 and the compressed air in the airchamber 11, and so gives to the Working piston 7 the stored up energy ofthe impact of the explosion of the charge, which is lost in all internalcombustion en ines having a fixed or immovable cylinder cad, fand acombustion chamber of unvarying volume. No part of the force of theexploding gases is here lost, except the unavoidable loss of heat byconvection and radiation throu h the walls of the cylinder; and thedirect e ect of storing up the energy .of this impact by the use ofthese improvements, as herein described, is to maintain a higher meanpressure on the working piston 7 throu hout its working or impulsestroke. ow, the

second out-stroke or impulse stroke of the? working piston 7 has beencompleted, and the exhaust valve is'opened mechanically when the gases,still under a pressure greater than the atmosphere, rush out through theNow the working piston 7 starts on exhaust openinflr 6. This causes thepressure of the gases in t e combustion chamber 12 to fall to that ofthe atmosphere; and the air piston 10, being relieved of this pressureon,

the side next the combustion chamber 12 and impelled by the pressure ofair in the air chamber 11, quickly completes its in-stroke. At the sametime, and while the burned gases are flowing from thecombustion-chamber, the working piston 7 makes its second instroke,commonly called the exhaust stroke, and at the completion of the stroke,the Working piston 7 and the air piston 1() are again in the positionshown in Fig. 1, being then very close together, and practicallyeffecting the complete expulsion of the burned or non-combustibleproducts of the previous explosion.

vIt is not essential that the air `piston be located in an extension ofthe main cylinder, for in some cases it may be in a separate chamber 14connected with the main cylinder by a passport 15, as shown in Fig. 3.

The foregoing description of the four phases of the Workin@ cycle onlyconteniplates the,` use of a ful charge of the explosive -mixture, fromwhich 1s obtained the maximum amount of work which the engine is capableof delivering. Now, let us consider the main object' of the invention,namely; means for varying theclearance space in which the combustion ofthe fuel takes place, by means of which-a fraction of the full chargemay be taken into the cylind'er and exploded at practically the samepre-com ression pressure as with a yfull charge, ut with a correspondingdecrease of able volume of the combustion chamber in proportion to thecharge taken in, byv the following means: At some convenient point on ornear the main cylinder 1 of the engine, is placed the air-reservoir 23.This air reservoir may containatmospheric air under pressure from an airpum o erated by the en- 1gine (preferably), or y and, or it may be lledwith the spent gases from theexhaust of the engine, which' will `giveythe necessary pressure, `Without a pump; orit may be filled with steamgenerated by the heat of the exhaust gases, or by a separate heater.Either air, spent gas or steam will work equally well for the purpose,provided the necessary pressure is maintained in ltheair reservoir Iprefer to use spent gas from the exhaust as the simplest means to thedesired end.

From the air reservoir 23 and connectingl :With the air chamber 11 ofthe engine, is a tube or pipe v'24 having an intervening air valve 25,and a check valve 26 adapted to control the flow of compressed air, lgasor steam'from the air reservoir to the air chamber. This air valve is tobe automatically o erated by the usual governor, or by hand, t eobjectbeing to increase the initialpressure of air, gas or steam in the airchamber at the same time with the corresponding de-v crease of chargetaken into the Working cylp inder ofthe engine. The open-ing of this airvalve may never be sufficient for an extreme change of charge from fullcharge to minimum charge else it might exceed the requirements of themore moderate changes of charge. It is rather intendedl to control,under moderate changesof charge at each explosion, or gradually for anyradical or .extreme change, re uiring probably five or six full workingcyc es of the engine to accomplish the complete change from full chargeto minimum charge. Also leading from thel air chamber 11 is the pass-Wayor port 27,v to Which is connected the auto-v matic relief valve 22,which is nothing more than the ordinarysafety pop valve common to allpressure service devices. This relief valve is adjustable to the reuir'ed maximum pressure of the exploding c arge in the com ustionchamber, which pressure Will also be present in the air chamber 11, andis adapted to open automatically when pressure into the air reservoir,and

this predetermined maximum pressure-has been reached, discharging theove lus; of eepmg the maximum pressure in the air chamber at the desiredpoint for all Working-conditions of the engine. Thus it Will be seenthat by means of the air valve 25, and the .supply of air, spent gas orstream lowing In an internal combustion engine, and in combination Withits Working piston, a second piston forming the opposing Wall of thecombustion chamber, a pneumatic cushion behindsaid second-piston andmeans for in= creasing and decreasing the resistance of said pneumaticcushion and allowing said second piston to move during the compresn sionof the charge.

In testimony whereof I have signed my name to this specification in thepresence of tWo subscribing Witnesses.

CHARLES DAVID MCCLINTOCK.

Witnesses:

WM. F. BOOTH, D.,B..RIcHARDs.

